1. Field of the Invention
The invention relates to valves and, more particularly, to an attenuating means to lower the noise level introduced by high pressure gas, steam or a liquid as it passes through a valve.
2. Description of the Prior Art
In attempting to reduce the noise level of valves to low noise levels that meet present day governmental and industrial standards, many different noise attenuating constructions for such valves have been devised. One such valve construction employs a plurality of stacked perforated discs. The flow passages in these discs are so staggered or spaced that the fluid passing therethrough travels in a tortuous path whereby the pressure drop across the valve is increased and its discharge velocity is reduced. Such an arrangement is shown in the K. S. Borg et al U.S. Pat. No. 3,780,767.
Perforated cages and perforated plugs through which the fluid is directed have likewise been utilized heretofore, such as is shown in U.S. Pat. No. 3,821,968.
Since the aforementioned perforated stacked discs and the aforementioned perforated cage and plug arrangements require the fluid passing through the valve to tunnel through many restricted passageways, such construction has a detrimental affect of limiting the velocity at which a fluid can flow through these valves.
Another problem that has heretofore been encountered with stacked disc type valves and the perforated plug-sleeve arrangement of the G. E. Barb U.S. Pat. No. 3,821,968 that contains perforated valve plug parts and an associated perforated cage is that there is a tendency for such valves to become clogged due to foreign matter in the fluid under control adhering to the walls forming the restricted passageways in these valves.